Electric control system for oil burners



Sept. 13, 1932.

J.- N. MACRAE ETYAL ELECTRIC CONTROL SYSTEM FOR OIL BURNERS Filed June7, 1929 1NVENToRS M ATToRNYs.

z BY Mz fm WQ QN Patented sept. 13, 1932 UNITED STATES PATENT OFFICEJAMES N. MACRAE AND CALVIN 1. PACKARD, 0F STAMFOBD, CONNECTICUT,.ASSIGNORS TO PETROLEUM HEAT AND IOWER COMPANY, OF NEW YORK, N. Y., ACORPORATION OF DELAWARE ELECTRIC CONTROL SYSTEM FOB OIL BBNEBS`Application led June 7, 1929. Serial No. 369,061.

This invention is directed to an improvement in oil burner controllingmechanism or an electric control system for oil burners and provides acontrolling mechanism which we believe embodies novel control featuresin the operation of oil burners by way of the control. for theignition,the venting of the fuel feed tank and opening of theline under abnormalconditions, etc, all of which will appear hereinafter. t

The drawing accompanying the application is diagrammatic.

Referring to the drawing in detail, l designates a room thermostat, 2 aboiler control thermostat, 3 a mercury line switch, and 4 an ignitiontransformer. 5 designates blower operated mechanism for control of theline switch 3. 6 is a combustion-controlled therniostatic switch.

Vith the parts in the position shown in the diagram, we will assume thatthe burner is not in operation. Consequently, the blade 7 of thecombustion-controlled switch 6 is on the contact 8. We will assume alsothat the room thermostat is calling for heat, and hence the blade 9thereof is on the Contact 10 and the blade 11 of the boiler controlswitch 2 is on the contact 12.

With the switches in these positions and under these conditions acircuit may be traced from cue side of the line, by way of conductors 13and 14 to the blade 7 ofthe switch 6, contact 8 of said switch,conductors 15 and 16, blade 11 and contact 12 of boiler control switch2, conductor 17, blade 9 and contact 10 of room thermostat 1, conductors18 and 19 to mercury switch 20, throu h this switch, conductor 21, coil22 of a o'uble wound switch-controlling solenoid 23,- conductors 24, 25,51, contact 73 of line switch `3, conductors 52 and 26 to the other sideof the line.

Energization of the coil 22 of solenoid 23 will effect movement of thecore 27 thereof to the left, as viewed in the drawing, into contact witha pivoted arm 28'carrying an ignition ,controlling mercury switch 29,tipping this switch upwardly to closed position, so that a circuit` willbe closed to the primary 3() of the ignition transformer 4 and astarting circuit to winding 31 of a double-switch and vent valvecontrolling solenoid 32.

The circuit to the transformer primary may be traced by way ofconductors 13 and 33, mercury switch 29, which is now closed, conductor34, primary 30, conductors 35, 25, 51, Contact 73, conductors 52 and 26,to the other side of the line.

The starting circuit for the winding 31 of the solenoid 32 may be tracedby way of conductors 13, 33, mercury switch 29, conductors 36, 37,winding 31, conductors 38, 38', 51, Contact 73, conductors 52 and 26, tothe other side of the line.

The exciting of the winding 31 causes the solenoid 32 to move its core39 upwardly, as viewed on the diagram, and through the connection shownat 4() simultaneously to rockv the mercury switches 2() and 41 upwardlyfrom the position shown on the diagram.

Thismovement of the switches 20 and`41 opens the circuit of the coil 22of solenoid 23lv at the contacts 42 in the rightthand end of mercuryswitch 20 and establishes through. the switch 41 a holding circuit forthe winding 31 of solenoid 32.

This holding circuit may be traced by way of conductors 13 and 43,mercury switch 41, conductors 44 and 16, boiler control switch 2,conductor 17, room thermostat 1, conductors 18 and 18, mercury switch20, conductors 45 and 37 winding 32, conductors 38, 38', 51, contact 73,conductors 52 and 26, to the other side of the line.

The energizing of the winding 31 of solenoid 32 closes a bleeder or ventvalve 46 which is connected through pipe 46' to a pressure feed fueltank, 46".

Inasmuch as the coil 22 of solenoid 23 has been energized, and the core27 thereof moved to the left to tip the switch 29, and inasmuch as themercury switch 41 has been tipped by.' energization of the winding ofsolenoid 32 a circuity has been completed through the motor 48, by wayof conductors 13- and 43, contacts 49 of mercury switch 41, conductor50, through the motor, conductors 48', 38', 51, mercury line switch 3,conductors-52 and 26, to the other side of the line.

T he closure of the circuit of the motor 48 will, of course, start thefan or blower 47 in operation to supply pressure to the feed tank 46 andair to the burner cup C.

Referring to the blower operated mechanism 5 for the control of the lineswitch 3, this mechanism comprises a cylinder 53 connected by pipe 54 tothe housing of blower 47, and a float cylinder 55 communicating with thecylinder 53 through conduit 56. The conduit 56 is controlled by a flapvalve 57, opening toward cylinder 53, this valve being provided with aport 58. The iiow ofliquid from 53 to 55 is necessarily slow, the liquidall passing through port 58, the iow in the opposite direction, however,being rapid, as in this direction of flow the valve is unseated.

Thecylinder 55 is provided with a float 59, having a stem 60, this stembeing provided with a member 6l adapted to cooperate with the right handendof the core 27 of solenoid 23. rlhe stern 60 is also provided with anoperating member 62 adapted to travel between two legs 63 and 64 of aswitch controlling lever 65, piyoted at 6 6, and adapted to control theline switch 3.

To the upperend of the stem 60 is attached a bleeder or vent valve 67for the float chamber or pressure feed fuel tank 46, this valve, as willbe understood, being additional to the bleeder or vent valve 46 abovereferred to and connected to the tank by pipe 67 With the parts in thepositions assumed and the circuits vtraced established the burner isready for operation and the starting up of the blower 47 will drive theliquid 68 out of the cylinder 53 through the port 58 in the flap valve47 into the cylinder 55 to cause the ioat 59 in this last cylinder torise and close the vent valve 67 on the fuel feed tank. Inasmuch as thecircuit of the motor 48 is closed prior to the closing of the vent valve67, it is apparent that the burner will receive air prior to receiving afuel supply, and consequently the burner cup C, if an air driven typeisused, will have an opportunity to be brought up to speed beforereceiving oil.

This is a desirable operation. The vent valves 46 and 67 being closed,as above described, pressure will be built up in the fuel feed tank andoil supplied to-the burner cup C through pipe P and the circuit to theprimary winding'30 of the ignition transformer 4 being closedfas abovenoted, the oil will be ignited. When combustion is initiated it will beapparent that the blade of switch 6, which as above pointed out iscontrolled by combustion conditions will be moved off of the contact 8and into engagement with a fixed contact 69, to close a circuit to asecond winding 70 for the solenoid 23 which is opposed to the winding22, the circuit of which has been broken, of this solenoid. The circuitfor this winding 70 may be traced by way of conductors 13, 14, switchblade 7, contact 69, conductor 71, winding 70, conductors 24, 25, 51,contact 73, conductors 52 and 26, to the other side of the line.

The core 27 of the solenoid 23, therefore, will move to the right,V asviewed in the diagram, until the 'right hand end thereof will beinterposed in the path of the member 61 being carried upwardly by thefloat stem 60, thereby to arrest the upward movement of this stem priorto the engaging of the member 62 on the stem with the upper arm 64 onswitch controlling lever 65. The movement of the core 27 under theaction of the winding will permit the ignition control mercury switch 29to open by gravity and hence open the circ-uit of the primary 30 of theignition transformer and the starting circuit of winding 31 of solenoid32. A holding circuit, previously traced, has already been establishedfor the Winding 31, so that the core of solenoid 32 remains in position.

Consequently we have a condition now Where the burner is in operation,the circuit of the ignition transformer open and the core of thesolenoid 23 in the path of the member 61 preventing further upward.movement thereof.

When the temperature of the room being heated has risen to the desireddegree, the blade 9 of the room thermostat 1 will move oil the fixedContact 10 and open the holding circuit for the winding 31 of thesolenoid 32, permitting the latter to drop its core, opening vent valve46 and permitting the two switches 20 and 41 to rock to the right sothat they will assume their original position shown on the drawing,which will effect an opening of the circuit of the motor 48, the blower47 will come to rest and the burner cease operation.

Under these conditions the liquid 68 inthe cylinder 55 will flow backtoward the cylinder 53 until the same level is reached in bothcylinders, interruption of the operation of blower 47 interrupting thesupplying of pressure tothe liquid68.

The two bleeder valves or vent valves 46 and 67 are now opened again,the former due to deenergization of solenoid 32 and the latter duetodescent of fioat 59, so that the flow of oil to the burner isinterrupted, the pressure on the fuel in this tank being relieved by theopening of the two vent valves.

When the room being heated cools ofi' sufficiently so that the roomthermostat again calls for heat the operation above described will berepeated.

If for any reason ignition should not be initiated on starting up, thepresent invention provides for opening one leg of the supply. Assumingthat the fuel did not ignite, it will be obvious that the blade 7 of thecombustion controlled switch 6 will remain on the 'fixed contact 8 andhence the circuit of the winding 70 of the solenoid 23 'will remain openand the core 27 of this solenoid will remain in its left hand position,that is in engagement with the lever 28 of switch 29, as will beundeistood. Consequentlyv the operation of the blower 4T will continueto force the liquid 68 out of the cylinder 53 and into the cylinder 55to movethe float 59 upwardly until the operating member 62 on the floatstem hits the upper arm 6l of the lever 65,

rocking the latter to the left about its pivot 66 yuntil itentirelydisengages the lever T2 which carries the line switch 3, and the latterwill rock open by gravity to open the motor 'circuit at the contacts T3of this switch. This of course will open one leg ofthe supply. In thisconnection it should be noted that to resume operation it is necessarythat the line control switch 3 be reset by hand.

It will be understood that in normal operation when the burner ceasesoperation due to the room temperature having reached the degree desiredthe motor circuit is opened at the room thermostat 1 before the switchblade T has moved otf the contact 69 so that the core :2T of thesolenoid 23 remains in its right hand position. otherwise this corewould be pulled to the left and instead of the circuit of the motor 4Sbeing opened, as is desired, it would be opened by the rising of thefioat 59 which will necessitate a manual resetting of the switch 3 eachtime.

In the event of power failure the lnotor 4S of course will stop andlikewise the blower -f' and if the )ower is otf the line for asullicient length of time the level of the liquid 68 in the cylinders 55and 53 willassume a level permitting the float 9to lower` therebyopening the vent valve 67 in the feed tank. The winding of the solenoid32 on power failure is also deenergized so that the vent valve 46 willlikewise open. Consequently the supplying of oil to the burner willcease and ,when the power comes on the line again, assuming i ofcoursethat the room thermostat 1 is still calling for heat, normal operationwill be automatically resumed.4

In the event of a leak in the float 59. the same will sink, causing themember 6:2 to strike lever arm 63, pivoting the upper end of'l lever 65to the right from beneath the member 72. The latter will drop by gravityand open the line at the contacts 73.

What we claim is: y

1. In an oil burner mechanism having an electric motor, a bloweroperated thereby, a fuel tank in communication with said blower to placethe fuel therein under air preure,

- a vent valve for the tank and a line switch for the motor circuit,means for operating the said line switch and vent valve comprisingliquid containing means, a connection therefromto the blower whereby airpressure will cause the liquid level to rise, a float controlled by saidliquid level. means operated by said tioat to close said vent valve andsubsequently after a predetermined time to open said line switch on risein liquidlevel and means responsive to combustion conditions to preventopening of said line switch.

Q. In a control systemf'for an oil burner mechanism having a source offluid pressure, a fuel tank in communication therewith to place the fueltherein under fluid pressure, and an electrically operated igniter, saidcontrol system comprising a vent valve for said tank, a solenoidoperative when energized for actuating said valve to close, a switch in-circuit with said igniter and solenoid and a second solenoid foractuating said switch.

3. In oil burner mechanism the combination of a burner motor, switchingmeans controlling the circuit of said motor, a solenoid for actuatingsaid switching means, an electrically operated igniter, a. switch deviceoperative when closedto energize said igniter and said solenoid, saidswitching means being operative when actuated by said solenoid to closea holding circuit forv said solenoid, a second solenoid having twowindings, the first of said windings actuating said switch device toclosed position, said switching means being operative when actuated tobreak the circuit of said first winding, the second of said windingsoperating when energized to release said switch device for openingmove-V ment, and a combustion controlled switch operative on initiationof combustion to energize said second winding.

4. A control system for an oil burner mechanism having a blower, anelectric motor to drive said blower, a fuel tank communicating with saidblower to place the fuel therein under pressure, said control systemcomprising a line switch operative when open to deenergize allelectrical elements, a vent valve for the fuel tank, means operated byblower preure to first close said vent valve and a time periodthereafter to open said line switch, and combustion responsive meansoperative on initiation of combustion within said time period to preventsaid blower operated means o ning said line switch.

This speci cation signed this 5th day of June,1929.

JAMES N. MACRAE. This specification signed this 5th day of June, 1929.

CALVIN P. PACKARD.

